Basics of the NBN

There are ALOT of questions surrounding the NBN at the moment, particularly with the new 3-year rollout schedule having just been thrust upon the world. But for a moment I want to step back and just answer some of the basics.

What is the NBN?

The NBN or National Broadband Network is, at its' heart, national telecommunications infrastructure. That is, in VERY basic terms, phone lines. Now, it is, of course, not that simple. Why, might you ask, would we need new phone lines? The one I'm using to view this blog works fine?? Indeed it does and they have served us well. But the phone lines we use have different sections and each has its' own benefits, problems and limitations. These issues with each section, which I will explain, determine the speed of broadband connection the end-customer can receive, through a measure called bandwidth (and also its' quality). Bandwidth is a measure of how much data can be downloaded from an internet location per second. It is usually expressed, in bits per second (Kilo (thousand) Mega (million), Giga (billion) and Tera (trillion)). Your average YouTube video on normal quality (480p) runs at about 750kbps.

Our Telecommunications lines

1- International/National Backbone Fibre Infrastructure- These are the lines that connect major Australian cities and regions and also Australia to the rest of the world. There are optical fibre main cables running to and from every capital city in Australia, as well as cities like Cairns, Broome, Gold Coast, Dubbo, Mildura, Bendigo, Kalgoolie and Alice Springs (and of course across the Bass Strait to our lovely Apple Isle). These are owned by a dozen or so different companies, with Optus C&W and Telstra being 2 larger operators (see ACCC Report 2001). There are also submarine cables running:

- Sydney-Melbourne-Perth-Singapore (SEA-ME-WE 3)
- Sydney-Port Moresby-Guam-Japan (APNG-2)
- Sydney-Guam-Japan (AJC)
- Sydney-New Caledonia (Gondwana-1)
- Sydney-Guam (PPC-1)
- Sydney-New Zealand-Fiji-Hawaii-California (Southern Cross Cable)
- Sydney-Jakarta (JASURAUS)- BACKUP

Many of these cables go on to link us to the rest of the world (Gondwana-1 links to Western Europe, AJC links to the US). The largest cables, in terms of bandwidth, are the Southern Cross Cable and SEA-ME-WE 3. Interestingly, until recently, alot of traffic across Australia (Sydney-Perth) went via these cables, so in fact talking to someone within your own country, involved virtually leaving it before coming back in on the other side- not particularly efficient.

These overseas links, many only installed within the last decade, are nowhere near their bandwidth limitations (the Southern Cross Cable alone is built for 6100 Gbps, but is only running at 800Gbps- See here)

2- The Internal Backbone (Backhaul)- These networks are what connects the various fibre nodes (end points or terminations of the backbone fibre lines), to the local exchanges or main exchanges to sub-exchanges. These are often a bewildering mix of last century fibre, copper and new dedicated modern fibre backbone (Telstra has alot of this). These are varying degrees of age and having wildly differing bandwidth capacities. (copper systems as low as several tens of Gbps, fibre in the high hundreds, just with current technology)- EDIT: Most is now Fibre, but also owned by Telstra and operators have to pay to use it. TPG acquired a fair amount of backhaul over the past 5 years also. This has enabled some small amount of competition on pricing for backhaul.

3- The PSTN or Public Switched Telephone Network- This is the part Telstra owns and operates almost exclusively. It is the copper cabling, running in conduit underground (or simply buried direct), the last few km's between the exchanges and the customer's premises. It's been estimated nearly 15% of the PSTN is badly damaged (reference); I know mine is! The bandwidth for broadband that a customer can get is largely determined by, 1) the distance along this cable from the exchange and 2) the integrity of that cable.

This graph from Internode shows the "theoretical bandwidth limits" falling as the distance from the exchange increases:

As you can see, if you live far from your local exchange, you're already at a disadvantage. You can also see under the main units of the x-axis is another set of units called "Line Attenuation." This and cable noise are what cause the vast majority of the speed drop in a normal ADSL or ADSL2+ connection. In basic terms line attenuation is the "resistance" of the line to signal and noise is anything on the line that interferes with your broadband signal.

Attenuation is mostly a property of the length/thickness of your line while noise comes from a number of sources including poor cable terminations, water in the line/conduit, RF interference, earth leakage and more. Signal-to-noise ratio is how this is measured (SNR) and if it is low, it indicates a poor quality connection (ie more noise in comparison to signal strength). Filters can remove a certain amount of noise on a line, but you will eventually hit a wall in terms of what signal you can extract from a poor line. You can find your attenuation (which should be low- 10dB or lower is good) and your SNR (which should be high- 10dB or lower is very poor) in your modem/router settings.

What's this got to do with the NBN??

And here we hit the nail on the head.  While it is true there is alot of upgrades going on to the main backbone and exchange linkages, in general, many millions of businesses and households are stuck on copper until/if Telstra or other providers decide to upgrade to HFC (Hybrid Fibre-Coaxial) or fullfat fibre. New estates are generally FTTN (Fibre-to-the-Node) as a minimum, which involves having fibre CLOSE to the house, but not to it and often full blown FTTH (Fibre-to-the-Home). Some CBD trials (like that in Melbourne) had Telstra rolling out HFC for several suburbs, but these upgrades have been few and far between as consumer demand for higher speeds is only modest in comparison with financial outlay for the upgrades. This is often used as an argument against the NBN, ie. it is not economically viable. While the debate still rages as to whether almost $40 Billion is too much to pay for the NBN, it can hardly be argued that what is not economically viable for business (and subsequently profit) is not economically viable for the Government whose sole purpose is to provide better services.

This is where the NBN comes in. The NBN will homogenise the entire system. All backbone links will be fibre. All exchange and node links will be fibre. And, most importantly, all consumer home lines will be fibre (called Fibre-To-The-Home; FTTH). To begin with, this VASTLY increases the speeds available to consumers. Current copper home lines degrade after less than 1km, are essentially useless after between 4 and 6km and have maximum speeds of approx. 25Mbps. HFC lines have speeds comparable to fibre (in the downstream ONLY. ie uploads are ADSL speed, not fibre speed), and have distance stamina lower, but comparable too, but require different hardware from copper lines, as does fibre. Fibre is good for 15km. And more with the correct equipment. (although currently, few exchanges need 15km of fibre to get to a premises)

It also increases UPstream data, that is, your upload AS WELL as your download speeds. So, if you're on an 8Mbps plan currently, you're unlikely to have anything faster, in terms of uploading, than 1Mbps (in fact that's the same regardless of what consumer plan you're on). Once the NBN is rolled out, uploads will VASTLY improve. So if you sign up for a 25Mbps plan, you will have 25Mbps down and 5/10 Mbps up. This is a GREAT boon for small businesses and large who host their own websites/offsite data. It will also reshape how households consume content; if you record tv on a PVR or computer at home and want to watch it at a friends? Currently, you're unlikely to get any decent sort of quality at your end. Under the NBN, it will be like watching it at home. (assuming your data cap can cope with it). Quotas will also vastly increase, because wholesale leasing from NBN will be speed based, not based on amounts of data flowing, so all ISP's will be on an even playing field, making data quotas one of the main competition points.

Fibre is also "theoretically" immune to interference of signal. This is primarily because copper cabling is solid, has impurities, heats up, and in general has all he problems associated with running a signal along a cable. Fibre uses light to transfer information. Each cable is wrapped in high opacity insulating plastic/gel, so little or no light can enter into the interior of the fibre. This means the light transfer has little, if anything, that can interfere with detecting the signal at the other end. So, although the light at the receiving end may be 1000 times dimmer (light is still constrained by the law of inverse squares) than at the sending end (although with repeaters in place this is unlikely) the signal can still be read and transfered in its much weakened state, as little or no noise has changed that signal. This means the quality of your signal will be essentially the same no matter your distance from your exchange.

The NBN will be a wholesale network (much like Telstra BEFORE it was sold off in 1996) that ALL other ISP's and telecoms companies will lease from (including Telstra). This will mean (wholesale) pricing, quality of service, maintenance and connections will all be handled by a single entity, unbiased towards any specific service or company. NBN is currently wholly owned by the Federal Government, but not run by them. It has its' own board and CEO and is independently operated. There are many overseas experts on the board and many more experts and contractors being consulted on the best way to rollout a very large and complicated FTTH network.

The NBN will produce a level playing field for all consumers and businesses, large or small, in terms of quality of service, bandwidth and wholesale pricing. Regardless of your political views, solid infrastructure can only be good. Arguments against it stem from expense, rollout scheduling and necessity.

More questions answered next post!

1 comment:

  1. NBN can be more effective in our way of life nowadays. Especially if the NBN Fibre broadband will cater all the places in whole Australia.